Till now the notification was limited to desktop based email services like Microsoft Outlook and Mozilla Thunderbird. SpyPig has taken it a step further and has extended the service to 
include web based email services like Gmail, Yahoo, Hotmail etc. Here is how it works-
In the form provided on their homepage:
- You enter your email address.
- Enter the message title.
- Select the Pig Image. [Basically this image is the way how this service tracks your message.]
- Select # of notifications to receive.
- Activate your profile.
- Copy-Paste the image in your email and send the email as usual.
- You will now be notified as soon as the receiver opens the email.
There are other services like ReadNotify.com but they are limited to 10 emails for free usage. SpyPig is completely free. Probably they make money from the ads shown on their home page.
The prerequisite is that the receiver should have open image option enabled in his mail settings.
Ankur Jain is a Software Engineer in Test Automation. After a 5 years stint with Accenture and Oracle, he started his eLearning company. A long-time blogger and proud owner of the "Learn" series of websites. 